1,783 research outputs found

    Can we rebuild the economic consensus?

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    There are times in history when the consensus about our economic system breaks down. It happened after the Long Depression, also known as the Great Depression of the 19th century, and again in the 20th century around the Great Depression of 1929-1933, as well as after the Great Recession of 2008-2009 that followed the global financial crisis. The Covid-19 great crash, which carries the risk of a deep downturn, has led governments to take extraordinary measures in all areas of our lives. This has further fuelled the need to discuss how to rebuild the consensus about the most appropriate economic system for the 21st century as the great question of our time

    SPT5 affects the rate of mRNA degradation and physically interacts with CCR4 but does not control mRNA deadenylation

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    The CCR4-NOT complex has been shown to have multiple roles in mRNA metabolism, including that of transcriptional elongation, mRNA transport, and nuclear exosome function, but the primary function of CCR4 and CAF1 is in the deadenylation and degradation of cytoplasmic mRNA. As previous genetic analysis supported an interaction between SPT5, known to be involved in transcriptional elongation, and that of CCR4, the physical association of SPT5 with CCR4 was examined. A two-hybrid screen utilizing the deadenylase domain of CCR4 as a bait identified SPT5 as a potential interacting protein. SPT5 at its physiological concentration was shown to immunoprecipitate CCR4 and CAF1, and in vitro purified SPT5 specifically could bind to CAF1 and the deadenylase domain of CCR4. We additionally demonstrated that mutations in SPT5 or an spt4 deletion slowed the rate of mRNA degradation, a phenotype associated with defects in the CCR4 mRNA deadenylase complex. Yet, unlike ccr4 and caf1 deletions, spt5 and spt4 defects displayed little effect on the rate of deadenylation. They also did not affect decapping or 5\u27 - 3\u27 degradation of mRNA. These results suggest that the interactions between SPT5/SPT4 and the CCR4-NOT complex are probably the consequences of effects involving nuclear events and do not involve the primary role of CCR4 in mRNA deadenylation and turnover

    Stoichiometry and Change of the mRNA Closed-Loop Factors as Translating Ribosomes Transit from Initiation to Elongation

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    Protein synthesis is a highly efficient process and is under exacting control. Yet, the actual abundance of translation factors present in translating complexes and how these abundances change during the transit of a ribosome across an mRNA remains unknown. Using analytical ultracentrifugation with fluorescent detection we have determined the stoichiometry of the closed-loop translation factors for translating ribosomes. A variety of pools of translating polysomes and monosomes were identified, each containing different abundances of the closed-loop factors eIF4E, eIF4G, and PAB1 and that of the translational repressor, SBP1. We establish that closed-loop factors eIF4E/eIF4G dissociated both as ribosomes transited polyadenylated mRNA from initiation to elongation and as translation changed from the polysomal to monosomal state prior to cessation of translation. eIF4G was found to particularly dissociate from polyadenylated mRNA as polysomes moved to the monosomal state, suggesting an active role for translational repressors in this process. Consistent with this suggestion, translating complexes generally did not simultaneously contain eIF4E/eIF4G and SBP1, implying mutual exclusivity in such complexes. For substantially deadenylated mRNA, however, a second type of closed-loop structure was identified that contained just eIF4E and eIF4G. More than one eIF4G molecule per polysome appeared to be present in these complexes, supporting the importance of eIF4G interactions with the mRNA independent of PAB1. These latter closed-loop structures, which were particularly stable in polysomes, may be playing specific roles in both normal and disease states for specific mRNA that are deadenylated and/or lacking PAB1. These analyses establish a dynamic snapshot of molecular abundance changes during ribosomal transit across an mRNA in what are likely to be critical targets of regulation

    The optimal polarizations for achieving maximum contrast in radar images

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    There is considerable interest in determining the optimal polarizations that maximize contrast between two scattering classes in polarimetric radar images. A systematic approach is presented for obtaining the optimal polarimetric matched filter, i.e., that filter which produces maximum contrast between two scattering classes. The maximization procedure involves solving an eigenvalue problem where the eigenvector corresponding to the maximum contrast ratio is an optimal polarimetric matched filter. To exhibit the physical significance of this filter, it is transformed into its associated transmitting and receiving polarization states, written in terms of horizontal and vertical vector components. For the special case where the transmitting polarization is fixed, the receiving polarization which maximizes the contrast ratio is also obtained. Polarimetric filtering is then applies to synthetic aperture radar images obtained from the Jet Propulsion Laboratory. It is shown, both numerically and through the use of radar imagery, that maximum image contrast can be realized when data is processed with the optimal polarimeter matched filter

    Detecting Bose-Einstein condensation of exciton-polaritons via electron transport

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    We examine the Bose-Einstein condensation of exciton-polaritons in a semiconductor microcavity via an electrical current. We propose that by embedding a quantum dot p-i-n junction inside the cavity, the tunneling current through the device can reveal features of condensation due to a one-to-one correspondence of the photons to the condensate polaritons. Such a device can also be used to observe the phase interference of the order parameters from two condensates.Comment: 5 Pages, 3 Figure

    End User Query Performance: The Interaction of User Characteristics and Information Request Ambiguity

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    This paper investigates the effects of personality characteristics on individuals’ abilities to resolve ambiguity in an information retrieval environment. In particular, this research examines the effects on query performance of the interaction of personality characteristics (as measured using the NEO PI-R) with information requests that contained extraneous, syntactic, or both extraneous and syntactic ambiguities. The results indicate that ambiguity affected performance. The results also show that various personality dimensions significantly affect end-users’ abilities to compose accurate queries. Neuroticism, agreeableness, openness to experience, and conscientiousness affected the number of errors made in the query formulations. Conscientiousness affected the length of time taken to compose the queries and neuroticism affected the confidence end users had in the accuracy of their queries. In addition, the results indicated that, while the personality dimensions affected performance, there was no interaction between the personality dimensions and ambiguity

    First report of NDM-1-producing acinetobacter baumannii in East Africa

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    Background: The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) was observed in a Kenyan hospital from 2009 to 2010. Further investigation of the dissemination of CRAB isolates and the molecular characterization of associated resistance determinants were therefore performed. Methods: Antibiotic susceptibilities were determined by broth microdilution and Etest. Metallo-blactamases were detected by Etest method. Clonal relationships were studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). b-Lactam and aminoglycoside resistance determinants and the clonal relatedness to widespread European clones were studied by PCR and sequencing. Results: Sixteen CRAB isolates from 10 patients possessed six pulsotypes; half of the isolates belonged to the European clone II (ECII) lineage. ECII strains were typed as MLST sequence type 2 (ST2) and ST109, and non-ECII strains as ST25 and ST113. All isolates harbored ISAba1–blaOXA-23, blaOXA-51-like, blaADC, and class 1 integron, including one that also harbored blaNDM-1. ADC-57 and two integron cassettes (arr-2- cmlA5 and aadB-aadA2-cmlA6-aadA15) were newly-identified. Non-ECII isolates, designated non-ECII clone, carried armA and integron cassette arr-2-cmlA5. Conclusions: Two distinct clones of CRAB – ECII and non-ECII epidemic clones – were disseminated in Kenya. The concomitance of ISAba1–blaOXA-23 was the major mechanism contributing to CRAB. The first identification of ECII CRAB and New Delhi metallo-b-lactamase 1 (NDM-1) extensively drug-resistant A. baumannii in East Africa is of concern

    Service Transformed: Illustrations of Women Veterans Past and Present

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140142/1/jwh.2015.5530.pd

    Entanglement detection via condition of quantum correlation

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    We develop a novel necessary condition of quantum correlation. It is utilized to construct dd-level bipartite Bell-type inequality which is strongly resistant to noise and requires only analyses of O(d)O(d) measurement outcomes compared to the previous result O(d2)O(d^{2}). Remarkably, a connection between the arbitrary high-dimensional bipartite Bell-type inequality and entanglement witnesses is found. Through the necessary condition of quantum correlation, we propose that the witness operators to detect truly multipartite entanglement for a generalized Greenberger-Horne-Zeilinger (GHZ) state with two local measurement settings and a four-qubit singlet state with three settings. Moreover, we also propose the first robust entanglement witness to detect four-level tripartite GHZ state with only two local measurement settings

    Polarimetric clutter modeling: Theory and application

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    The two-layer anisotropic random medium model is used to investigate fully polarimetric scattering properties of earth terrain media. The polarization covariance matrices for the untilted and tilted uniaxial random medium are evaluated using the strong fluctuation theory and distorted Born approximation. In order to account for the azimuthal randomness in the growth direction of leaves in tree and grass fields, an averaging scheme over the azimuthal direction is also applied. It is found that characteristics of terrain clutter can be identified through the analysis of each element of the covariance matrix. Theoretical results are illustrated by the comparison with experimental data provided by MIT Lincoln Laboratory for tree and grass fields
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